What is the role of magnet therapy in the perioperative management of permanent pacemakers (PPMs) and automatic implantable cardioverter-defibrillators (AICDs)?

Updated: Oct 29, 2018
  • Author: Albert H Tsai, MD; Chief Editor: Sheela Pai Cole, MD  more...
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One of the most common CIED interventions in the intraoperative period is placement of a magnet over the device. This is typically effective, but to avoid harming the patient, it is imperative to have a clear understanding of the effects of the magnet on the CIED and to knowg when to pursue further workup.

As noted (see above), knowing whether the patient has a PPM or an AICD is crucial because the two device types respond differently to magnet therapy. Whereas placing a magnet over a PPM generally converts it to asynchronous pacing at a preset rate, placing a magnet over an AICD generally turns off its defibrillator function without affecting its pacemaker function (ie, does not convert it to asynchronous pacing). Thus, a pacer-dependent patient with an AICD remains vulnerable to inappropriate sensing due to EMI despite magnet therapy, and internal reprogramming is required before surgery. Furthermore, different CIED brands vary in terms of their specific responses to magnet therapy. [7]

If magnet therapy on a PPM yields no response, the possibility of malpositioning or a depleted battery should be considered. A lower-than-expected paced rate after magnet placement over a PPM is consistent with low battery life and may warrant additional interrogation. Additionally, certain AICDs (eg, those from St Jude Medical and Boston Scientific) may be programmed to ignore magnet therapy, in which case the defibrillator function will remain active despite magnet placement.

When AICDs are deactivated, either via magnet therapy or through internal reprogramming, external defibrillator pads must be placed on the patient to ensure the availability of antitachycardic therapy.

When magnets are removed after surgical procedures, PPMs and AICDs typically revert to their respective baseline settings; however, interrogation must be performed postoperatively to confirm ther return of baseline CIED function. An unmonitored patient left in asynchronous pacing is at high risk for an R-on-T phenomenon, and an AICD whose defibrillator function is turned off may prove fatal in a patient requiring antitachycardic therapy.

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